Cementitious binder



Patented Apr. 4, 1950 muss KttttitNUl:

CEMENTITIOUS BINDER Conral G. Callis, Manheim, Pa., assignor toArmstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania NoDrawing.

Application December 13, 1945,

Serial No. 634,900

Claims.

This invention relates to heat insulating blocks and method of makingthe same. This application is a continuation-in-part of my co-pendingapplication Serial No. 476,058, filed February 16, 1943, Patent No.2,396,246, which is in turn a continuation-in-part of my co-pendins,applications Serial Nos. 380,815, filed February 27, 1941, and 336,963,filed May 24, 1940, both now abandoned.

The present invention is directed to the amme%tilizing a binder formedby the reac on a peratures between about 32 F. and about 125 F. of awater soluble alkali metal aluminate and an alkaline earth oxide.

It is an object of the invention to provide heat insulating blockshaving good resistance to rupture under bending and compressive stressesat all temperatures to which such blocks are customarily subjected.

It is a further object of the invention to provide a heat insulatingblock having low thermal conductivity at the elevated temperaturesoccurring in installations where the blocks are used.

These objectives are accomplished by combining a filler materialpreferably of a heat resistant character and a binder made by thereaction in a water slurry at temperatures between about 32 F. and about125 F. of an alkali metal aluminate and a hydrated alkaline earth oxide.It appears that the alkaline earth oxide combines with the alkali metalaluminate in the presence of moisture at such temperatures to form acementitioussubstance which acts as a binder for the filler material.

The alkaline earth oxide which may be used in my process may be that ofcalcium, barium, magnesium, stronium, as well as a mixture of any ofthese, such as a calcium-magnesium oxide mixture made from dolomite. Thecalcium oxide or the calcium-magnesium oxide mixture are prefenedbecause of their ready availability and low cos The alkali metalaluminate may be of sodium or potassium although any of the other alkalimetal aluminates may be used if and when they become commerciallyavailable. Mixtures of alkali metal aluminates may also be used.

In order to obtain a satisfactory binder it has been found that theproportion oi. the hydrated alkaline earth oxide to the alkali metalaluminate should be on the basis of about three mols of hydratedalkalineearth oxide (calculated as alkaline earth oxide) to about two mols ofalkali metal aluminate. Of course, there may be an excess of either ofthe constituents but, in view of the cost of the alkali metal aluminate,it is preferable to use but two mols to each three mols of the hydratedalkaline earth oxide. An excess of the hydrated alkaline earth oxidewill not be objectionable since its cost is relatively low. but sincethe chemical reaction which occurs requires the molar ratio recitedabove, there is no necessity for incorporating an excess of either ofthe ingredients. As a matter of fact, the binder which is formed by thereaction product will in no event contain more than three mols of thehydrated alkaline earth oxide to two mols of the alkali metal aluminateeven though an excess of the oxide may be present but uncombined.

In order to obtain a block having the desired strength characteristicsthe binder should be present in the finished product in a quantity fromabout ten percent to about forty percent by weight based upon the weightof the total solids in the raw slurry. The precise quantity of binderemployed will depend to a considerable extent upon the type of filler orfillers incorporated in the block, the strength and conductivitycharacteristics necessary in the finished product, and other variablefactors.

Either the lkaline earth hydroxides or the alkaline eart oxides ma beemployed as startingm'fieh mmsadded to wateiit is immediately hydratedwith the evolution of heat and the slurry should be cooled to at leastabout 125 F. before the alkali metal aluminate is added to the slurry.The reaction is between the alkaline earth hydroxide and the alkalimetal aluminate and it should be accomplished at temperatures betweenabout 32 F. and about 125 F. I prefer to operate at temperatures betweenabout 50 F. and F., ordinary room temperatures and the range in whichtap water is generally available, but as pointed out above satisfactoryresults are obtained when the temperature is between about 32 F., thefreezing point of the water, and about F., above which a substantialamount of line powder havine substantially no binding value is obtained.Between 100 F. and 125 F. some powder is formed but not in objectionablequantities. Optimum results are obtained between about 50 F. and 85 F.In some instances it may be desirable to apply heat to the slurry,particularly if the temperature is down in the neighborhood of freezingso as to accelerate the reaction. As pointed out above,

in other instances it may be desirable to cool the EXAMINER dration.

the raw slurry is adequate.

The main body of the filler material is preferably diatomaceous cambercalcined or raw, exfoliated vermicuor other inorganic filler materials,with about ten percent of fiber.

The i llarunx wholly fibrous o in particles if desired.

Winlt e inder consists essentially of the reaction product at roomtemperatures of the alkali metal a-luminate and the hydrated alkalineearth oxide, other cementitious materials may be added such as clay,aluminous cement, basic magnesium carbonate, and self-setting crystalsof normal magnesium carbonate (MgCO3.3H2O or MECO3.5H20) Any desiredorder of mixing may be utilized. However, it is preferred to add thefiller materials during the latter part of the mixing proc- :30

ess. Preferably the binder is formed by reacting the binder ingredientsin the presence of the filler although the binder may be prepared inadvance and mixed with the filler materials. The consistency of theslurry which is formed may vary widely depending upon the method offorming Obviously a larger amount of water will be necessary if a filterpress is used to form the block while less water will be necessary ifhand molding methods are employed. While it is preferred to employ somepressure (up to about forty pounds per square inch) in forming the blockor cake from the slurry, because the final blocks as so made havegreater strength in proportion to the degree of pressure used;nevertheless, blocks or cakes formed by permitting the solids to set inthe slurry while it is in an aqueous condition and without use ofpressure to press water therefrom, possess sufiicient strength for somepurposes. heating to an elevated temperature in the neighborhood of 150F. to 400 F. The elevated temperature is not used to efiectuate thereaction between the alkaline earth oxide and the alkali metalaluminate. about room temperature and temperatures thereabove should beavoided to produce a well bonded, light weight material having goodinsulating The drying of the block subsequent to the reaction of thebinder ingredients facilitates the removal of uncombined water from thepressed and reacted block.

the blocks.

properties.

The following examples are illustrative of the' invention.

The blocks may be dried by This reaction takes place at Example 1 Aslurry containing 64 pounds of calmneuirth, 8 pounds of awn-fiber.

m gggggsnea and pounds of binder produced by combining three mols ofhydrated calcium oxide and two mols of immate is made up in 50 allons ofmag thoroughly.

'4 added with continued mixing and the asbestos fibers are incorporated.The slurry is then pumped to a filter press where the water is removedto form a rough block. The rough block is dried and then sized to thedesired dimensions.

Example 2 A slurry is made of 8.4 pounds of sodium aluminate and 13.2pounds of slacked lime (equivalent to 10 pounds of calcium oxide) inabout gallons of water. The ingredients are permitted to react at roomtemperature and a jelly-like cementitious mix is formed. Sixteen poundsof this binder (on a solids basis) are mixed in about gallons of waterand 56 pounds of raw diatomaceous earth, and 8 pounds of fibrous fillermaterial such as asbestos fiber, mineral wool or glass wool fibers arethen added with continuous mixing. The slurry is pumped to a filterpress where the water is removed to form a rough block. This block isthen dried and sized to desired dimensions.

Example 3 A slurry is made up containing 16.8 pounds of sodium aluminateand 26.4 pounds of slacked lime in about 50 gallons of water. Thisproduces about 32 pounds of binder on a solids basis. To this is addedpounds of vermiculite and 8 pounds of asbestos fiber or its equivalent.The slurry is continuously mixed during the incorporation of the variousingredients and is then pumped to a filter press where the water is re-'moved to form a rough block. The rough block is dried and then sized tothe desired dimensions.

In Example 1 above, the binder constitutes about ten percent by weightbased on the weight of the solid materials; in Example 2 about 20percent; and in Example 3 about 40 percent. In each instance the binderis formed by the reaction at room temperatures of three mols of hydratedalkaline earth oxide, calculated as alkaline earth oxide, and two molsof alkali metal aluminate. The temperature of the slurry in allinstances is between 32" F. and 125 F.

The heat insulating block produced by this invention may be used atelevated temperatures up to about 1800 F. when calcined diatomaceousearth or vermiculite is used and about 1500" F. when raw diatomaceousearth is used. The insulation may be used wherever a heat resistantmaterial having low heat conductivity is required.

While I have described certain preferred embodiments in my invention Ido not wish to be limited thereto since the invention may be otherwiseembodied and practiced within the scope of the following claims.

I claim:

1. A cementitious binder material consisting essentially of the productobtained by reacting at a temperature between about 32 F. and about 125F., a water slurry of a on ree mols of hydrated alkaline earth oxide,calculated as alkaline earth oxide, and about two mols of an alkalimetal aluminate which is reactive with the hydrated alkaline earth oxideat such temperature.

2. A cementitious binder consisting essentially of the product obtainedby reacting at a temperature between about F. and about 85 F., a 70water slurry of about three mols of hydrated alkaline earth oxide,calculated as alkaline earth oxide, and about two mols of an alkalimetal alurninate which is reactive with the hydrated alkaline earthoxide at such temperature.

3. A cementitious binder consisting essentially CROSS REFERENCE of theproduct obtained by reacting at a temperature between about 32 F. andabout 125 F., a water slurry of about three mols of calcium hydroxide,calculated as calcium oxide, and about two mols of an alkali metalaluminate which is reactive with the calcium hydroxide at suchtemperature.

4. A cementitious binder consisting essentially of the product obtainedby reacting at a temperature between about 32 F. and about 125 F., awater slurry of about three mols of calcium hydroxide, calculated ascalcium oxide, and about two mols of sodium aluminate which is reactivewith the calcium hydroxide at such temperature.

5. A cementitious binder consisting essentially of the product obtainedby reacting at a tempera- 6 ture between about 32 F. andabout 125 F., awater slurry of about three mols of hydrated alkaline earth oxide,calculated as alkaline earth oxide, and about two mols of sodiumaluminate which is reactive with the hydrated alkaline earth oxide atsuch temperature.

CONRAL C. CALLIS.

REFERENCES CITED Name Date Callis Mar. 12, 1946 Number EXAMINER

1. A CEMENTITIOUS BINDER MATERIAL CONSISTING ESSENTIALLY OF THE PRODUCTOBTAINED BY REACTING AT A TEMPERATURE BETWEEN ABOUT 32*F. AND ABOUT125*F., A WATER SLURRY OF ABOUT THREE MOLS OF HYDRATED ALKALINE EARTHOXIDE, CALCULATED AS ALKALINE EARTH OXIDE, AND ABOUT TWO MOLS OF ANALKALI METAL ALUMINATE WHICH IS REACTIVE WITH THE HYDRAFTED ALKALINEEARTH OXIDE AT SUCH TEMPERATURE.